The present invention relates to a support structure in a turbine or compressor device. The invention further relates to a method for assembling such a support structure.
The term turbine device is intended to mean a machine in which the energy present in a flowing fluid (gas, vapor or liquid) is converted into rotational energy by means of blades or vanes. The term compressor device is intended to mean a machine having an inverse function, that is to say rotational energy is converted by means of blades or vanes into kinetic energy in a fluid. The device comprises a rotor and a stator interacting therewith.
In the following, the device comprises a turbine device, which in turn forms part of a gas turbine. This is a preferred but in no way restrictive application of the invention. The term gas turbine is intended to mean a unit which at least comprises a turbine wheel and a compressor wheel driven by the former, together with a combustion chamber. Gas turbines are used, for example, as engines for vehicles and aircraft, as prime movers for vessels and in power stations for generating electricity.
The rotor may take the form both of a radial rotor and an axial rotor.
The term elongate rotor member is here intended to mean the rotor shaft and any further components intended to rotate on the rotor shaft, such as bearings and spacers between the bearings and gears.
For the support of the rotor member in the stator member of a turbine or compressor and for allowing the high speed flow of gas through the engine the support structure includes a number of radially inner and outer support rings, the inner and outer rings being interconnected by means of radially extending struts. Down stream relative to at least some of the struts flap airfoils are positioned, see for example U.S. Pat. No. 6,619,916, and the interrelationship between the struts and corresponding flaps necessiates a thorough positioning of the struts. For different reasons the inner and outer support rings are preferably manufactured as separate components by casting metal alloy. The struts can be made by metal alloy extrusion or by forming a sheet metal as separate components which are assembled by welding or soldering at each ends with the inner ring and the outer ring. However casting involves normally high tolerances and problems with the accurate positioning of the struts relative to the flap airfoils.
It is desirable to provide a support structure which provides an accurate positioning of the struts between the inner and outer ring.
According to an aspect of the present invention, a support structure in a turbine or compressor engine for rotatably supporting a rotor member in a stator member includes an inner ring, an outer ring, and a plurality of struts which extend radially between the inner ring and the outer ring, at least one of the rings having integrated portions projecting in a direction of the struts and forming end connections for the struts, wherein the end connecting portions of the at least one of the rings are together with the ring made by casting a metal alloy having initially oversized cross sectional dimensions relative to the cross sectional dimensions of a corresponding strut and having at least one lateral surface worked for removing material so as to achieve final dimensions and positioning to conform to the cross sectional dimensions and positioning of each corresponding strut.
According to another aspect of the present invention, a method for assembling a support structure in a turbine or compressor engine for rotatably supporting a rotor member in a stator member is provided, the support structure including an inner ring, an outer ring and a plurality of struts which extend radially between the inner ring and the outer ring, at least one of the rings having integrated portions projecting in a direction of the struts and forming end connecting portions for the struts. According to the method, the end connecting portions of the at least one of the rings are cast together with the ring using a metal alloy having initially oversized cross sectional dimensions relative to the cross sectional dimensions of corresponding strut. At least one lateral surface is worked for removing material, so as to achieve final dimensions and positioning to conform to the cross sectional dimensions and positioning of each corresponding strut.
By forming an integrated over-sized projecting portion of the inner and/or outer ring and determining the accurate position of each strut where-after the projecting portion can be finally determined as to its position and dimensions by material working off part of each projection.